arch/um/drivers/line.c: safely iterate over list of winch handlers

unregister_winch() should use list_for_each_safe(), as it can delete from
the list.

Signed-off-by: Will Newton <will.newton@gmail.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 1664cce7b0ac..050e4ddbbb65 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -821,12 +821,12 @@ void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
 
 static void unregister_winch(struct tty_struct *tty)
 {
-        struct list_head *ele;
+        struct list_head *ele, *next;
         struct winch *winch;
 
         spin_lock(&winch_handler_lock);
 
-        list_for_each(ele, &winch_handlers) {
+        list_for_each_safe(ele, next, &winch_handlers) {
                 winch = list_entry(ele, struct winch, list);
                 if (winch->tty == tty) {
                         free_winch(winch, 1);